An unusual location for heterotopic ossification: lumbar anterior longitudinal ligament

Heterotopic ossification (HO) is a well known complication of spinal cord injury. It usually affects the hips and knees, with less common involvement of the shoulders and elbows. We present a patient with incomplete tetraplegia who developed HO in the left hip and in the plane of the lumbar anterior longitudinal ligament from L3 to L5. During evaluation for the patient's complaints of low back pain, a fracture was noted in the HO which was confirmed by three-dimensional CT scan. We postulate that this fracture contributed to his symptoms. Review of the literature on HO in spinal cord injured patients indicates this to be an unusual location for HO. Although HO of the lumbar anterior longitudinal ligament is a rare occurrence, this possibility should be considered in the evaluation of back pain in spinal cord injured patients.